What is the bearing static safety factor s0?

The static safety factor s0 is the ratio of the basic static load rating C0 to the actual static equivalent load P0. It ensures the bearing does not suffer permanent deformation under static or shock loads. s0 = C0 / P0.

What minimum s0 should I use?

Use the current guideline table of the exact bearing manufacturer. The value depends on ball/roller type, motion, load certainty, shock and the acceptable effect of permanent deformation or quiet-running requirement. This calculator does not assign a universal minimum.

What happens if s0 is too low?

If s0 is below the recommended minimum, the bearing may develop permanent indentations (brinelling) in the raceways. This leads to increased noise, vibration, and premature fatigue failure.

How do I determine P0?

Use the ISO 76 method or the current product table for the exact bearing. X0, Y0, applicability conditions and any radial/axial comparison depend on bearing type and design; do not use one generic equation for every bearing.

When should static load capacity be checked?

Check static capacity for stationary or slowly oscillating bearings and for peak, shock or impact loads, including peaks in otherwise rotating service. Dynamic rating-life analysis does not replace this check.

Free Engineering Tool #045

Bearing Static Safety Factor Calculator

Calculate s₀=C₀/P₀ using catalog C₀ and a correctly determined P₀. Select the required minimum from current manufacturer guidance.

ISO 76:2006 + Amd 1:2017 s₀ = C₀/P₀ No Universal PASS/FAIL

Results

Static Safety Factor s₀

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Static Safety Factor

Per ISO 76, the static safety factor is the ratio of the basic static load rating to the actual static equivalent load:

C₀ — basic static load rating (kN), from bearing catalog
P₀ — static equivalent load (kN), calculated from actual radial & axial forces

Selecting the required factor

ISO 76:2006 specifies static ratings/equivalent load and includes guidance for heavily loaded applications. Manufacturer tables add application distinctions. Do not collapse them into a single ball/roller threshold.

ISO 76 calculations may be unsatisfactory for truncated contact, abnormal load distribution, misalignment, preload, extra-large clearance, coatings or special surface treatments. Consult the manufacturer in those cases.

Practical Example

Worked ratio example — stated catalog values

Given: C₀ = 31.5 kN, P₀ = 12 kN, normal operation

s₀ = 31.5 / 12 = 2.63

Compare s₀=2.63 with the applicable current manufacturer guideline; this arithmetic alone does not establish PASS/FAIL.

ℹ️ Scope: Static capacity should also be checked for known peak, shock or impact loads in otherwise rotating service. Dynamic rating life does not replace the static check.

The procedures described on this page were developed and field-tested by the Vibromera team using the Balanset-1A, a portable dual-channel balancer and vibration analyzer for on-site rotor balancing.